I found a new way to make lots of cookies!
I plant the full 6x6 garden full of Bakeberries, aside from one plot where I plant a Tidygrass to ensure I don't get weeds. (although I'm not sure that is necessary)
I wait till I get a golden cookie frenzy combined with a building frenzy.
Once I do, I harvest the entire garden at once.
Then I top it off by casting the "Conjure baked goods" spell twice.
Afterwards I wait until all frenzies are done and then I replant the garden. (because the price of seeds also depends on the rate of cookies per second)
I have found that this process easily nets me (at the moment, because it is dependent on the rate of cookies per second) over 100 sextillion cookies or even over 200 sextillion. As a matter of fact, while I was writing this post I was fortunate enough to harvest on a frenzy + grandma frenzy combo and my cookies in bank went from about 846 sextillion to about 1075 sextillion. This included two times 4.36 sextillion for the baked goods spell, so roughly 220 sextillion for the harvesting alone. Using this new technique, I have been able to go from about 650 sextillion cookies baked all-time to over 2 septillion in a matter of days, definitely less than a week. I wish I had thought of this a long time ago.
You can actually do this a few times a day if you're lucky (and you pay attention of course), as long as you use the various types of soil to your advantage. I.e. use fertilizer in order to get the Bakeberries to mature the quickest and then use clay once they are mature in order to prolong their lifespan. Of course freezing the garden can also come in handy in order to prevent the mature bakeberries from dying of old age while you're say off at work or asleep.
Now I finally have amassed enough cookies in my bank to be able to purchase the "Kitten accountants" upgrade. I am very curious as to what this is going to do to my cookies per second.